On average, an American can expect to enjoy about 78 years of life on this planet, according to a report by the United Nations. Factors such as genetic predisposition and lifestyle choices can extend or abbreviate this amount of time, but did you know that the area in which you live can play a part as well? Here, the states with the shortest life expectancies, as determined by the U.S. Census Bureau and supported by data from the Centers for Disease Control and Prevention (CDC), U.S. Department of Health and Human Services, and the Death Penalty Information Center (DPIC).

1. District of Columbia. Perhaps since state and world affairs weigh heavy over their heads, people residing in the nation's capital live a mere 72.6 years, but it's more likely due to the polluted air and homicide rates, which are the highest in the country. Washington, D.C., also sees the highest incidence of prostate cancer and diabetes, and the district ranks third among states with the heaviest drinkers.

2. Mississippi. Boasting the highest rate of obesity in the United States, Mississippi is in a dead heat with the District of Columbia for the greatest occurrence of diabetes per capita and the most people living below the poverty line; a Mississippian tends to live only about 73.7 years.

3. Louisiana. Not only is 30 percent of Louisiana's population obese; it also ranks ninth among states with the highest overall cancer rates, has some of the highest murder stats, and its capital, Baton Rogue, is among the most polluted cities. No wonder a Louisianan has a life expectancy of just 74.4 years.

4. Alabama. Subject to a prevalence of heart disease and diabetes and an obesity rate of 28.1 percent, inhabitants of the Heart of Dixie, 24.8 percent of whom are smokers, will be lucky if they live to a meager 74.6 years old.

5. South Carolina. The Palmetto State has the highest crime rate, and 28.5 percent of its population is obese, which are probably major contributors to an average South Carolinian's life span of 74.9 years.

6. and 7. Tennessee and West Virginia. Residents of both these states are expected to live an even 75 years. Tennessee has a high incidence of obesity, heart disease, and diabetes, and it ranks third among states with the most smokers. West Virginia is the second most obese state in the nation.

8. Arkansas. The state's obesity, diabetes, cancer, and heart disease statistics are remarkably high. To make matters worse, 15.6 percent of its people live in poverty, which might further explain why residents of Arkansas live only about 75.1 years.

9. and 10. Kentucky and Oklahoma. Considering that the Bluegrass State has the most smokers, the highest incidence of lung cancer among men, and a population that is 27.4 percent obese (plus one of its major cities, Lexington, creates the highest carbon footprint of all major U.S. metropolises), it's actually surprising that Kentuckians live to the relatively ripe old age of 75.3. And not one but two of Oklahoma's urban centers made it onto the American Podiatric Medical Association's list of the 10 Worst Walking Cities of 2008-Oklahoma City at No. 1 and Enid at No. 6. That, combined with a prevalence of heart disease and a notable suicide rate (the 11th highest in the nation), surely play a role in its top 10 spot.